Electrostatic protection circuit with impedance matching for radio frequency integrated circuits

ABSTRACT

An electrostatic-discharge/impedance-matching circuit for use in radio frequency (RF) integrated circuits. The electrostatic-discharge/impedance-matching circuit includes at least one shunt circuit operable to shunt current related to an over-voltage condition and at least one series element operably coupled to the shunt element. The shunt element and series element in combination provide electrostatic discharge protection for the RF signal processing circuit elements on the integrated circuit and also provide a matched input impedance for an incoming RF signal. Various alternate embodiments of die electrostatic-discharge/impedance-matching circuit include first and second shunt elements and a series element operably connected in combination to provide optimal electrostatic discharge protection and impedance matching. The electrostatic-discharge/impedance-matching circuit can be placed at various locations on the integrated circuit to provide optimal petformance depending on the particular architecture of the integrated circuit.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Utility application Ser. No.10/172,913, filed Jun. 17, 2002, which issued on Aug. 3, 2004 as U.S.Utility Pat. No. 6,771,475).

FIELD OF THE INVENTION

This invention relates generally to communication systems and, moreparticularly, to circuitry for providing electrostatic protection andimpedance matching for radio frequency circuit components in integratedcircuits.

BACKGROUND OF THE INVENTION

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), wireless application protocols (WAP), local multi-pointdistribution systems (LMDS), multi-channel-multi-point distributionsystems (MMDS), and/or variations thereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel (e.g., one of the plurality of radiofrequency (RF) carriers of the wireless communication system) and shareinformation over that channel. For indirect wireless communications,each wireless communication device communicates directly with anassociated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the receiver receives RFsignals, removes the RF carrier frequency from the RF signals via one ormore intermediate frequency stages, and demodulates the signals inaccordance with a particular wireless communication standard torecapture the transmitted data. The transmitter converts data into RFsignals by modulating the data in accordance with the particularwireless communication standard and adds an RF carrier to the modulateddata in one or more intermediate frequency stages to produce the RFsignals.

As the demand for enhanced performance (e.g., reduced interferenceand/or noise, improved quality of service, compliance with multiplestandards, increased broadband applications, et cetera), smaller sizes,lower power consumption, and reduced costs increases, wirelesscommunication device engineers are faced with a very difficult designchallenge to develop such a wireless communication device. Typically, anengineer is forced to compromise one or more of these demands toadequately meet the others.

Costs of manufacturing a radio frequency integrated circuit (IC) may bereduced by switching from one integrated circuit manufacturing processto another. For example, a CMOS process may be used instead of a bi-CMOSprocess since it is a more cost effective method of IC manufacture, butthe CMOS process increases component mismatches, increases temperaturerelated variations, and increases process variations.

Two problems commonly encountered in the design and manufacture of RFsignal integrated circuits relate to impedance matching of various RFsignal processing components and control of electrostatic discharges toprevent damage to components inside the integrated circuit. Properimpedance matching is important for an efficient transfer of signal andenergy from a “source” to a “load.” In an integrated circuit forprocessing RF signals, impedance matching is especially important toensure an efficient transfer of an RF signal from the antenna to areceiver filter module or a low-noise amplifier.

Electrostatic discharges are well known as a major contributing factorin damaging integrated circuits—both during the manufacturing processand during use of the circuit. Integrated Circuits often come intocontact with accumulated static charge on surfaces such as the humanbody and assembly equipment. The voltage potential that accompanies suchbuilt up static charge is often on the order of Kilovolts. Whenaccumulated static charge finds a discharge path through the pins of anintegrated circuit, often through contact, electrostatic dischargeoccurs. These events can result in highly concentrated currents thatcause severe heating in the physical circuit devices of an integratedcircuit. Severe heating can cause permanent damage to these devices.Therefore, protective circuits or structures must be employed to preventdamage caused by electrostatic discharge. Electrostatic protectioncircuits must be capable of quickly and efficiently routingelectrostatic discharge between any combination of pins of an integratedcircuit, eliminating significant voltage differential and preventingdamage to circuit devices.

Therefore, a need exists for circuit that can be optimized to provideboth impedance matching and protection from the damaging effects ofelectrostatic discharges.

SUMMARY OF THE INVENTION

The electrostatic-discharge/impedance-matching circuit disclosed hereinfor use in radio frequency (RF) integrated circuits substantially meetsthese needs and others. The electrostatic-discharge/impedance-matchingcircuit of the present invention is broadly comprised of at least oneshunt circuit operable to shunt current related to an over-voltagecondition and at least one series element operably coupled to the shuntelement. The shunt element and series element in combination provideelectrostatic discharge protection for the RF signal processing circuitelements on the integrated circuit and also provide a matched inputimpedance for an incoming RF signal. Various alternate embodiments ofthe electrostatic-discharge/impedance-matching circuit include first andsecond shunt elements and a series element operably connected incombination to provide optimal electrostatic discharge protection andimpedance matching.

The electrostatic-discharge/impedance-matching circuit can be placed atvarious locations on the integrated circuit to provide optimalperformance depending on the particular architecture of the integratedcircuit. In one embodiment, theelectrostatic-discharge/impedance-matching circuit it located between atransmitter/receiver switch module and an antenna receiving incoming RFsignals. In another embodiment, theelectrostatic-discharge/impedance-matching switch is located directlybetween an antenna and a receiver filter module. In other embodiments,the electrostatic-discharge/impedance-matching circuit is locatedbetween a receiver filter module and a low-noise amplifier.

Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic block diagram of a wireless communicationsystem that supports wireless communication devices in accordance withthe present invention.

FIG. 2 illustrates a schematic block diagram of a wireless communicationdevice in accordance with the present invention.

FIG. 3 illustrates a schematic block diagram of a radio module of awireless communication device incorporating anelectrostatic-discharge/impedance-matching circuit in accordance withthe present invention.

FIG. 4 illustrates a schematic block diagram of an alternate embodimentradio module of a wireless communication device incorporating anelectrostatic-discharge/impedance-matching circuit in accordance withthe present invention.

FIG. 5 illustrates a schematic block diagram of a second alternateembodiment of a radio module of a wireless communication deviceincorporating an electrostatic-discharge/impedance-matching circuit inaccordance with the present invention.

FIG. 6 illustrates a schematic block diagram of a third alternateembodiment radio module of a wireless communication device incorporatingan electrostatic-discharge/impedance-matching circuit in accordance withthe present invention.

FIG. 7 illustrates a schematic block diagram of a fourth alternateembodiment radio module of a wireless communication device incorporatingan electrostatic-discharge/impedance-matching circuit in accordance withthe present invention.

FIG. 8 illustrates a schematic block diagram of the functionalcomponents of an electrostatic-discharge/impedance-matching circuit inaccordance with the present invention.

FIG. 9 illustrates a schematic block diagram of an alternate embodimentof an electrostatic-discharge/impedance-matching circuit in accordancewith the present invention.

FIG. 10 illustrates a flowchart diagram of a method for using theelectrostatic discharge and impedance matching circuit of the presentinvention to process an incoming radio frequency signal.

DETAILED DESCRIPTION

FIG. 1 is a schematic block diagram illustrating a communication system10 that includes a plurality of base stations and/or access points12–16, a plurality of wireless communication devices 18–32 and a networkhardware component 34. The wireless communication devices 18–32 may belaptop host computers 18 and 26, personal digital assistant hosts 20 and30, personal computer hosts 24 and 32 and/or cellular telephone hosts 22and 28. The details of the wireless communication devices will bedescribed in greater detail with reference to FIG. 2.

The base stations or access points 12–16 are operably coupled to thenetwork hardware 34 via local area network connections 36, 38 and 40.The network hardware 34, which may be a router, switch, bridge, modem,system controller, et cetera provides a wide area network connection 42for the communication system 10. Each of the base stations or accesspoints 12–16 has an associated antenna or antenna array to communicatewith the wireless communication devices in its area. Typically, thewireless communication devices register with a particular base stationor access point 12–14 to receive services from the communication system10. For direct connections (i.e., point-to-point communications),wireless communication devices communicate directly via an allocatedchannel.

Typically, base stations are used for cellular telephone systems andlike-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio and/or is coupled to a radio. The radio includes a highlylinear amplifier and/or programmable multi-stage amplifier as disclosedherein to enhance performance, reduce costs, reduce size, and/or enhancebroadband applications.

FIG. 2 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device 18–32 and anassociated radio 60. For cellular telephone hosts, the radio 60 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 60 may be built-in or anexternally coupled component.

As illustrated, the host device 18–32 includes a processing module 50,memory 52, radio interface 54, input interface 58 and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data), theradio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, digital receiver processingmodule 64, an analog-to-digital converter 66, a filtering/attenuationmodule 68, an IF mixing down conversion stage 70, a receiver filter 71,a low-noise amplifier 72, a transmitter/receiver switch 73, a localoscillation module 74, memory 75, a digital transmitter processingmodule 76, a digital-to-analog converter 78, a filtering/gain module 80,an IF mixing up conversion stage 82, a power amplifier 84, a transmitterfilter module 85, and an antenna 86. The antenna 86 may be a singleantenna that is shared by the transmit and receive paths as regulated bythe Tx/Rx switch 73, or may include separate antennas for the transmitpath and receive path. The antenna implementation will depend on theparticular standard to which the wireless communication device iscompliant.

The digital receiver processing module 64 and the digital transmitterprocessing module 76, in combination with operational instructionsstored in memory 75, execute digital receiver functions and digitaltransmitter functions, respectively. The digital receiver functionsinclude, but are not limited to, digital intermediate frequency tobaseband conversion, demodulation, constellation demapping, decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, constellation mapping, modulation,and/or digital baseband to IF conversion. The digital receiver andtransmitter processing modules 64 and 76 may be implemented using ashared processing device, individual processing devices, or a pluralityof processing devices. Such a processing device may be a microprocessor,micro-controller, digital signal processor, microcomputer, centralprocessing unit, field programmable gate array, programmable logicdevice, state machine, logic circuitry, analog circuitry, digitalcircuitry, and/or any device that manipulates signals (analog and/ordigital) based on operational instructions. The memory 75 may be asingle memory device or a plurality of memory devices. Such a memorydevice may be a read-only memory, random access memory, volatile memory,non-volatile memory, static memory, dynamic memory, flash memory, and/orany device that stores digital information. Note that when theprocessing module 64 and/or 76 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry. The memory 75stores, and the processing module 64 and/or 76 executes, operationalinstructions corresponding to at least some of the functions illustratedin FIGS. 3–10.

In operation, the radio 60 receives outbound data 94 from the hostdevice via the host interface 62. The host interface 62 routes theoutbound data 94 to the digital transmitter processing module 76, whichprocesses the outbound data 94 in accordance with a particular wirelesscommunication standard (e.g., IEEE802.11a, IEEE802.11b, Bluetooth, etcetera) to produce digital transmission formatted data 96. The digitaltransmission formatted data 96 will be a digital base-band signal or adigital low IF signal, where the low IF typically will be in thefrequency range of one hundred kilohertz to a few megahertz.

The digital-to-analog converter 78 converts the digital transmissionformatted data 96 from the digital domain to the analog domain. Thefiltering/gain module 80 filters and/or adjusts the gain of the analogsignal prior to providing it to the IF mixing stage 82. The IF mixingstage 82 directly converts the analog baseband or low IF signal into anRF signal based on a transmitter local oscillation 83 provided by localoscillation module 74. The power amplifier 84 amplifies the RF signal toproduce outbound RF signal 98, which is filtered by the transmitterfilter module 85. The antenna 86 transmits the outbound RF signal 98 toa targeted device such as a base station, an access point and/or anotherwireless communication device.

The radio 60 also receives an inbound RF signal 88 via the antenna 86,which was transmitted by a base station, an access point, or anotherwireless communication device. The antenna 86 provides the inbound RFsignal 88 to the receiver filter module 71 via the Tx/Rx switch 77,where the Rx filter 71 bandpass filters the inbound RF signal 88. The Rxfilter 71 provides the filtered RF signal to low-noise amplifier 72,which amplifies the signal 88 to produce an amplified inbound RF signal.The low-noise amplifier 72 provides the amplified inbound RF signal tothe IF mixing module 70, which directly converts the amplified inboundRF signal into an inbound low IF signal or baseband signal based on areceiver local oscillation 81 provided by local oscillation module 74.The down conversion module 70 provides the inbound low IF signal orbaseband signal to the filtering/attenuation module 68. Thefiltering/attenuation module 68 may be implemented in accordance withthe teachings of the present invention to filter and/or attenuate theinbound low IF signal or the inbound baseband signal to produce afiltered inbound signal.

The analog-to-digital converter 66 converts the filtered inbound signalfrom the analog domain to the digital domain to produce digitalreception formatted data 90. The digital receiver processing module 64decodes, descrambles, demaps, and/or demodulates the digital receptionformatted data 90 to recapture inbound data 92 in accordance with theparticular wireless communication standard being implemented by radio60. The host interface 62 provides the recaptured inbound data 92 to thehost device 18–32 via the radio interface 54.

As one skilled in the art will appreciate, the wireless communicationdevice of FIG. 2 may be implemented using one or more integratedcircuits. For example, the host device may be implemented on oneintegrated circuit, the digital receiver processing module 64, thedigital transmitter processing module 76 and memory 75 may beimplemented on a second integrated circuit, and the remaining componentsof the radio 60, less the antenna 86, may be implemented on a thirdintegrated circuit. As an alternate example, the radio 60 may beimplemented on a single integrated circuit. As yet another example, theprocessing module 50 of the host device and the digital receiver andtransmitter processing modules 64 and 76 may be a common processingdevice implemented on a single integrated circuit. Further, the memory52 and memory 75 may be implemented on a single integrated circuitand/or on the same integrated circuit as the common processing modulesof processing module 50 and the digital receiver and transmitterprocessing module 64 and 76.

It will be understood by those skilled in the art that the variouscircuit components illustrated in FIG. 2 can be constructed on amonolithic integrated circuit. The individual integrated circuitcomponents can be damaged by electrostatic discharge over-voltageconditions that are often created on the boundary of the integratedcircuit and conducted through the integrated circuit connecting pins.While the advantages of the electrostatic-discharge/impedance-matchingcircuit of the present invention can be obtained by placing the circuitin a multitude of locations on the integrated circuit, there areparticular advantages associated with locating it at the boundary of theintegrated circuit to prevent damage associated with electrostaticdischarges transmitted through the integrated circuit connecting pins.In each of the embodiments described herein, theelectrostatic-discharge/impedance-matching circuit may be formed upon anintegrated circuit at a boundary of the integrated circuit. Formed atthe boundary of the integrated circuit, theelectrostatic-discharge/impedance-matching circuit provides protectionfrom electrostatic-discharge at a respective input and alsoimpedance-matching at the respective input.

FIG. 3 illustrates an embodiment of the present invention wherein theelectrostatic-discharge/impedance-matching circuit 100 is connectedbetween the Tx/Rx switch module 73 and the antenna 86. Theelectrostatic-discharge/impedance-matching circuit 100′, shown inphantom, illustrates a connection of the circuit 100 to the Rx filtermodule 71 during operation when the Tx/Rx switch module 73 connects theantenna 86 to the Rx filter module 71. In the illustration shown in FIG.3, all of the circuit components of the radio 60 are formed (“on-chip”)on a single integrated circuit and theelectrostatic-discharge/impedance-matching circuit 100 is located on theboundary of the chip to protect against damage from static discharges atthe input connection where the an inbound RF signal is received from theantenna 86.

As will be discussed in greater detail below, theelectrostatic-discharge/impedance-matching circuit 100 comprises acombination of circuit components that provide matched input impedanceto the antenna 86. Further, theelectrostatic-discharge/impedance-matching circuit 100 may also providedesired output impedance to the RF filter module 71. While thecomponents of the electrostatic-discharge/impedance-matching circuit 100can be selected to provide a wide range of matching impedances,depending on the specific application, typical matched impedance aspresented to the antenna 86 is 50 ohms.

FIG. 4 illustrates an embodiment of the present invention wherein theelectrostatic-discharge/impedance-matching circuit 100 is connectedbetween the Rx filter module 71 and the low-noise amplifier 72. In theillustration shown in FIG. 4, the circuit components for the Tx/Rxswitch module 73, the Tx filter module 85 and the Rx filter module areformed “off-chip,” while all of the other circuit components of theradio 60 are formed on a single integrated circuit. Theelectrostatic-discharge/impedance-matching circuit 100 is, therefore,located on the boundary of the chip to protect against damage fromstatic discharges at the input connection where an inbound RF signal isreceived from the Rx filer module 71. Theelectrostatic-discharge/impedance-matching circuit 100 comprises acombination of circuit components that provide matched input impedanceto the Rx filter 71. The electrostatic-discharge/impedance-matchingcircuit 100 may also provide a desired output impedance to the low-noiseamplifier 72.

FIG. 5 illustrates an embodiment of the present invention in a radio 60that does not comprise a Tx/Rx switch module. In this embodiment, theoutbound RF signal 98 from Rx filter module 85 is transmitted on antenna86, while the inbound RF signal 88 is received on a separate antenna 86a. The electrostatic-discharge/impedance-matching circuit 100 isconnected between the antenna 86 a and the input to the Rx filter module71. In the illustration shown in FIG. 5, all of the circuit componentsof the radio 60 are formed on a single integrated circuit and,therefore, the electrostatic-discharge/impedance-matching circuit 100 islocated on the boundary of the chip to protect against damage fromstatic discharges at the input connection where the an inbound RF signalis received from the antenna 86 a.

FIG. 6 illustrates another embodiment of the present invention whereinthe electrostatic-discharge/impedance-matching circuit 100 isincorporated into a radio 60 that utilizes separate transmit and receiveantennas 86 and 86 a, respectively. In this embodiment, theelectrostatic-discharge/impedance-matching circuit 100 is connectedbetween the Rx filter module 71 and the low-noise amplifier 72. In theillustration shown in FIG. 6, the circuit components for the Tx filtermodule 85 and the Rx filter module are formed “off-chip,” while all ofthe other circuit components of the radio 60 are formed on a singleintegrated circuit. The electrostatic-discharge/impedance-matchingcircuit 100 is, therefore, located on the boundary of the chip toprotect against damage from static discharges at the input connectionwhere an inbound RF signal is received from the Rx filer module 71.Again, as discussed in connection with previous embodiments, theelectrostatic-discharge/impedance-matching circuit 100 comprises acombination of circuit components that provide a predetermined impedancethat provides a matched impedance between the output of the Rx filter 71and the input to the low-noise amplifier 72.

FIG. 7 illustrates another embodiment of the present invention whereinthe electrostatic-discharge/impedance-matching circuit 100 isincorporated into a radio 60 that utilizes separate transmit and receiveantennas 86 and 86 a, respectively. In this embodiment, theelectrostatic-discharge/impedance-matching circuit 100 is connectedbetween the low-noise amplifier 72 and the down-conversion module 70. Inthe illustration shown in FIG. 7, the circuit components for the poweramplifier module 84, the Tx filter module 85, the Rx filter module 71and the low-noise amplifier 72 are formed “off-chip,” while all of theother circuit components of the radio 60 are formed on a singleintegrated circuit. The electrostatic-discharge/impedance-matchingcircuit 100 is, therefore, located on the boundary of the chip toprotect against damage from static discharges at the input connectionwhere an inbound RF signal is received from the low-noise amplifier 72.Again, as discussed in connection with previous embodiments, theelectrostatic-discharge/impedance-matching circuit 100 comprises acombination of circuit components that provide a matched input impedanceto the low-noise amplifier 72.

FIG. 8 is a schematic block diagram illustration of an embodiment of theelectrostatic-discharge/impedance-matching circuit 100 comprising ashunt impedance 102 and a series impedance 104. As will be appreciatedby those of skill in the art, the impedance values of the shuntimpedance 102 and the series impedance 104 can be selected to optimizethe dissipation of electrostatic discharges at the RF input through theshunt impedance 102 to the ground line 105. Moreover, the combinedimpedance of the shunt and series impedance elements 102 and 104, canalso be optimized to provide impedance matching between the RF input andthe RF circuit component 107, which can be an Rx filter module 71,low-noise amplifier 72 or other RF circuit component on the boundary ofthe integrated circuit module.

FIG. 9 is a schematic block diagram illustration of another embodimentof the electrostatic-discharge/impedance-matching circuit 100 comprisinga first and second shunt impedance elements 102 and 106, respectively,and a series impedance 104. The first shunt element 102 is connectedbetween the RF input and Vss and the second shunt element 106 isconnected between the RF input and Vdd. As discussed above, it will beappreciated by those of skill in the art that the impedance values ofthe first and second shunt impedances 102, 106 and the series impedance104 can be selected to optimize the dissipation of electrostaticdischarges at the RF input. Furthermore, the combined impedance of thefirst and second shunt impedances and series impedance can also beoptimized to provide impedance matching between the RF input and the RFcircuit component 107, which can be an Rx filter module 71, low-noiseamplifier 72 or other RF circuit component on the boundary of theintegrated circuit module. Various discrete circuit components, known tothose skilled in the art, can be combined to obtain the desiredimpedances for each of the shunt and series impedance elements discussedabove. By was of illustration, shunt element 102 is shown to comprise adiode and resistor combination, while shunt element 106 is shown tocomprise a resistor, inductor and capacitor combination.

FIG. 10 is a flowchart illustration of the processing steps for usingthe electrostatic-discharge/impedance-matching circuit of the presentinvention to process an incoming RF signal. In step 200, an incoming RFsignal at a first impedance is obtained from an antenna, such as antenna86 or from an RF circuit component, such as Rx filter 71. In step 202the incoming RF signal is processed using theelectrostatic-discharge/impedance-matching circuit 100 to generate an RFsignal at a second impedance that is matched to the input impedance ofan RF circuit element. In step 204, the RF signal at the secondimpedance is provided to an RF circuit element in the wireless receiverfor further signal processing.

The preceding discussion has presented a circuit for providingelectrostatic discharge and impedance matching that may be used in aradio transmitter or radio transceiver. As one of skill in the art willappreciate, other embodiments may be derived from the teaching of thepresent invention, without deviating from the scope of the claims.

1. A wireless communication device comprising: a case; an antenna; and aradio at least partially contained in the case and comprising: abaseband processor; an RE front end circuit formed in an integratedcircuit and having an antenna interface; and an electrostatic dischargecircuit formed in the integrated circuit and communicatively coupledbetween the antenna and the antenna interface of the RF front endcircuit, wherein the elecirostatic discharge circuit is operable toprotect the RF front end circuit from an over-voltage condition andwherein the electrostatic discharge circuit provides a matched impedanceto the antenna, the electrostatic discharge circuit comprising: at leastone shunt circuit operable to shunt current related to an over-voltagecondition, the at least one shunt circuit including an over voltageclamp and an impedance matching shunt element; and at least one serieselement operably coupled to the at least one shunt element including atleast one impedance matching series element.
 2. The wirelesscommunication device of claim 1, further comprising a host deviceinterface communicatively coupled to the radio.
 3. The wirelesscommunication device of claim 1, wherein the radio supports wirelesslocal area network communications.
 4. The wireless communication deviceof claim 1, wherein the radio supports wireless personal area networkcommunications.
 5. The wireless communication device of claim 1, whereinthe radio supports cellular wireless network communications.
 6. Thewireless communication device of claim 1, wherein the electrostaticdischarge circuit provides a matched impedance of 50 ohms to theantenna.
 7. The wireless communication device of claim 1, furthercomprising a user interface.
 8. The wireless communication device ofclaim 1: further comprising a switch module formed in the integratedcircuit; wherein the electrostatic discharge circuit couples between theantenna and the switch module; and wherein the switch module couplesbetween the antenna interface of the RF front end circuit and theelectrostatic discharge circuit.
 9. The wireless communication device ofclaim 1, further comprising a switch module formed external to theintegrated circuit and coupled between the antenna and the electrostaticdischarge circuit.
 10. The wireless communication device of claim 1,further comprising: a switch module communicatively coupled to theantenna; and a filter module communicatively coupled between the switchmodule and the electrostatic discharge circuit.
 11. The wirelesscommunication device of claim 10, wherein: the RF front end circuitfurther comprises a receive filter formed in the integrated circuit; andwherein the electrostatic discharge circuit communicatively couplesbetween the antenna and the receive filter.
 12. A wireless communicationdevice comprising: a case; an antenna for receiving an inbound RFsignal; an RF front end receiver formed in an integrated circuit andhaving an input that receives and processes the inbound RF signal; andan electrostatic discharge circuit formed in the integrated circuit andconnected between the antenna and the input of the RF front endreceiver, wherein the electrostatic discharge circuit is operable toprotect the RF front end circuit from an over-voltage condition andwherein the electrostatic discharge circuit provides a matched inputimpedance to the antenna, the electrostatic discharge circuitcomprising: at least one shunt circuit operable to shunt current relatedto an over-voltage condition, the at least one shunt circuit includingan over voltage clamp and an impedance matching shunt element; and atleast one series element operably coupled to the at least one shuntelement including at least one impedance matching series element. 13.The wireless communication device of claim 12, further comprising a hostdevice interface communicatively coupled to the radio.
 14. The wirelesscommunication device of claim 12, wherein the RF front end receiversupports wireless local area network communications.
 15. The wirelesscommunication device of claim 12, wherein the RF front end receiversupports wireless personal area network communications.
 16. The wirelesscommunication device of claim 12, wherein the RF front end receiversupports cellular wireless network communications.
 17. The wirelesscommunication device of claim 12, wherein the electrostatic dischargecircuit provides a matched impedance of 50 ohms to the antenna.
 18. Thewireless communication device of claim 12, further comprising a userinterface.
 19. The wireless communication device according to claim 12,wherein the electrostatic discharge circuit comprises a single input anda single output.
 20. The wireless communication device of claim 12,wherein the electrostatic discharge circuit comprises a single input andfirst and second differential outputs.